Diel vertical migration of zooplankton in the Tanzanian waters of lake Victoria

The diel vertical migration of zooplankton was studied in the Southern part of Lake Victoria in January and July 2002. A van dorn water sampler was used to collect zooplankton. In January 2002, zooplankton showed a pronounced diel vertical migration whereby zooplankton were moving upward at around sunset and swimming downward at sunrise. In July 2002 zooplankton showed diel vertical migration, but at around midnight Thermodiaptomus galeboides, Thermocyclops emini, Tropocyclops tenellus, cyclopoid copepodites, nauplius larvae and some rotifers showed downward movement. The diel vertical migration of zooplankton seems to be influenced by food, predation and light. Tanzania Journal of Science Vol.30(1) 2004: 123-134